What Is the Safety Triangle? (Definition)
The safety triangle — also called Heinrich's Triangle, the accident pyramid, or the safety pyramid — is a model that shows the relationship between minor events, near misses, serious injuries, and fatalities. It suggests that severe incidents are often preceded by many lower-severity warning events.
The model is used as a prevention tool: if organisations learn from near misses and minor incidents at the base of the pyramid, they can reduce the likelihood of life-changing injuries at the top.
Heinrich's 1-29-300 Accident Pyramid
H.W. Heinrich published his well-known ratio in 1931 after analysing industrial accident data. His model is commonly summarised as:
| Level | Heinrich Ratio | Meaning |
|---|---|---|
| Major injury | 1 | One serious or major injury |
| Minor injuries | 29 | Twenty-nine minor injuries |
| No-injury accidents | 300 | Three hundred near misses or no-injury events |
Heinrich also argued that many incidents involved unsafe acts, which is why behaviour-based observation became influential in safety management.
Bird's 1-10-30-600 Ratio
In 1969, Frank E. Bird Jr. expanded the concept after reviewing a much larger dataset. Bird's accident ratio is usually presented as:
| Level | Bird Ratio | Meaning |
|---|---|---|
| Serious or major injury | 1 | Fatality, permanent disability, or serious harm |
| Minor injuries | 10 | Medical or first-aid injuries |
| Property damage incidents | 30 | Damage without injury |
| Near misses | 600 | No-loss or near-miss events |
The exact ratios vary by industry, but the principle is the same: the base of the pyramid contains the largest and most useful prevention dataset.
Safety Triangle vs Accident Pyramid: Key Differences
| Term | Meaning | Practical Use |
|---|---|---|
| Safety triangle | General prevention model linking minor events to major harm | Explains leading indicators |
| Heinrich's Triangle | 1931 ratio of 1 major injury, 29 minor injuries, 300 no-injury events | Classic accident prevention reference |
| Bird Pyramid | 1969 expanded ratio of 1-10-30-600 | Stronger emphasis on near misses and property damage |
Why the Safety Triangle Matters
The safety triangle matters because fatalities and serious injuries are statistically rare, but near misses and unsafe conditions are frequent. Waiting for recordable injuries gives safety teams too little data and too little time to act.
When organisations investigate base-of-pyramid events, they can identify recurring hazards, unsafe behaviours, weak controls, and system failures before they escalate. OSHA and modern EHS guidance both emphasise proactive reporting, investigation, and correction of near misses.
How AI and Computer Vision Strengthen the Safety Triangle
Traditional safety-triangle programmes depend on manual reporting, which means the base of the pyramid is often undercounted. Safvr uses computer vision to detect near misses, PPE gaps, forklift-pedestrian conflicts, line-of-fire exposures, blocked exits, and unsafe behaviours automatically.
Real-time alerts, video evidence, behaviour analytics, and trend dashboards help EHS teams see the true base of the accident pyramid and act before risk reaches the top.
How Safvr Helps You Use the Safety Triangle for Prevention
Safvr helps organisations convert safety-triangle theory into daily prevention. Key capabilities include:
- Continuous detection of near misses and low-severity warning events
- Automatic logging with timestamped video evidence and location context
- Trend dashboards showing recurring base-of-pyramid risks
- Real-time alerts for high-risk behaviours and unsafe conditions
- Predictive prevention workflows that prioritise controls before injuries occur